Representing Northern Peatland Hydrology and Biogeochemistry within the Community Land Model

Abstract:

Northern peatlands are projected to become very important in future carbon-climate feedback due to their large carbon storage and vulnerability to changes in hydrology and climate impacts. Understanding the hydrology and biogeochemistry is a fundamental task for projecting the fate of massive carbon stores in these systems under future climate change. Models have started to address microtopographic controls on peatland hydrology, but none have considered a prognostic calculation of water table dynamics in vegetated peatlands rather than prescribed regional water tables. We introduced here a new configuration of the Community Land Model (CLM), which includes a fully prognostic water table calculation between hummock and hollow microtopography in a vegetated peatland. We further integrated the hydrology treatment with vertically structured soil organic matter pools, and a newly developed microbial functional group-based methane module. The model was further used to test against observational data obtained within Spruce and Peatland Responses Under Climatic and Environmental Change (SPRUCE) project. Results for water table dynamic, carbon profile, and land surface fluxes of carbon dioxide and methane were reasonable. Model simulations showed that warming and elevated CO2 had significant impacts on land surface fluxes of methane and carbon dioxide. The warming-induced hydrological changes are another factors influencing biogeochemistry along soil profiles and land surface gas fluxes. These preliminary results provide some insights for field experiments as well as data-model comparison in next phase of the SPRUCE project.